We investigated the effect of BoNT/A injection on hip lateralisation in children with bilateral spastic cerebral palsy and bilateral adductor spasticity. Pelvic radiographs using Reimers' migration index (MI) were evaluated from 27 children (n=9 females, n=18 males; mean age 5.2±1.96 years; range: 2-10 years; initial MI <50%) with bilateral spastic cerebral palsy over a time period of 2 years. All received injections of BoNT/A (Dysport (®)) every 12 weeks with a dose of 30 Units per kilogram body weight into adductor and medial hamstring muscles on both sides. The MI was calculated before treatment and after 1 and 2 years. The mean MI increased from 25.5% (range: 0-48) to 26.7% (+1.2%, range: 0-79) on the right side and from 28.0% (range: 0-40) to 30.6% (+2.6%, range: 3-84) on the left side over 2 years, respectively. Hips of one patient dislocated bilaterally. The mean MI remained stable over 2 years. Although a specific BoNT/A effect cannot be proven because of the open design of this study, we provide strong evidence that the MI can be kept stable for a time period of 2 years under non-surgical management including therapy with BoNT/A even in CP patients with a high risk for hip dislocation.